Electronically Controlled Fuel Pump (EKP Fuel Pump)

Electronically Controlled Fuel Pump

The electronically controlled fuel pump system controls the electric fuel pump (EKP) as required. The fuel rate required by the engine at any time is converted by the electronically controlled fuel pump system into the required capacity of the EKP.

Brief description of components

Control module
The EKP control module is located in the luggage compartment on the right-hand side beside the wheel arch. The EKP control module controls the speed of the EKP by means of pulse width modulation of the EKP output voltage according to the fuel request. The supply characteristic curve of the EKP for the corresponding model series is stored in the coding data. The EKP control module ensures reliable activation of the EKP up to a system voltage including 6 V.

The Digital Engine Electronics (DME) control module transmits the request for the currently required fuel rate to the EKP control module.

Diagnosis CAN
The communication of the EKP control module with the DME control module takes place across the diagnosis CAN. The required fuel rate is passed on to the EKP control module by the DME control module in a message across diagnosis CAN.

Electric fuel pump (EKP)
The EKP is located in the fuel tank.

Function
The EKP control module controls the EKP according to the system mode of the fuel supply system in the operation of the vehicle. The fuel output rate of the EKP is activated and regulated according to a given characteristic curve via engine speed recognition. The reference variables for this are the fuel requirement of the engine and the fuel circuit systems.

The DME control module determines the fuel requirement of the engine and adds an additional quantity for operation of the suction jet pump (SSP). The total required amount of fuel is transmitted as a message across the diagnosis CAN to the EKP control module.

The EKP control module converts the received diagnosis CAN message into a pulse-width modulated output voltage for the EKP and thus controls the speed of the EKP.

The EKP control module is activated via terminal 15. This is followed by the initialization in which the EKP to activated 100 %. On completion of the initialization, the EKP control module regulates the EKP according to the supply rate set by the DME.

Emergency operation
If there is no communication with the DME or this is defective, the EKP control module switches to emergency operation. The electric fuel pump is fully activated.

IMPORTANT: Always ensure that the EKP control module is mounted according to regulations! Correct mounting ensures reliable heat dissipation. If this is not the case, it leads to overheating of the EKP control module and its failure. The result will be a breakdown.

During repair work on the fuel system, the EKP system has to be de-energized (risk of fire). To do so, either unplug the fuse in the rear distribution box or disconnect the plug connector to the electronic fuel pump at the fuel tank.